Rotary incinerating kilns are used for disposing of organic liquid-like hazardous waste. Typically, some such kilns are batch fed and have a fuel and/or waste fired primary flame in a region close to an inlet where containers filled with the hazardous material are loaded into the kiln. The kiln includes a rotating cylinder having a generally horizontal axis, with a diameter of 10 to 20 feet and a length to diameter ratio of about 3 or 4 to 1. The cylinder axis is tilted downwardly by a few degrees so that the hazardous waste is transported by gravity and kiln rotation from the inlet to an outlet of the kiln. The cylinder is rotated at slow speed, such as one revolution in five minutes. Typically, the total residence time of solid materials resulting from incineration of the hazardous waste in the kiln is about a half hour. The containerized hazardous waste is typically loaded into drums ranging in size from 1 to 55-gallons. The use of smaller containers has the disadvantage of increased hazardous waste handling by personnel loading and handling the containers. The hazardous waste containers are periodically supplied to the kiln at a relatively low rate. Typically, only a small cross section of the kiln is occupied by the hazardous waste and its residue, on the order of 1-2 percent. Waste feed rate is also limited by the heating valve of the waste in each drum.
The contents of a drum containing the hazardous waste and possibly a sorbent, such as ground corn cobs, sawdust or vermiculite, are usually volatilized during a period extending from the first seconds to few minutes of residence time of the drum and waste in the kiln. Residue of the waste and the drum are further incinerated and decomposed to form ash.
A transient phenomenon involving heat transfer into and waste mass transfer out of the waste promotes rapid release of waste vapor into the gas phase environment of the kiln. This rapid vapor release depletes and displaces excess oxygen from the primary flame to cause formation of a "puff" of incompletely or partially incinerated waste comprising undestroyed principal organic hazardous constituents, products of incomplete combustion and organic particulates, i.e., soot. If these components of the puff cannot be destroyed by an afterburner responsive to gases flowing out of the kiln or isolated by pollution control devices downstream of the kiln, there may result a temporary failure of an incinerator system of which the rotary kiln is a part.
Our research has shown that these "puffs" are caused by the rapid release of waste material into the gas phase. This waste quickly consumes the available oxygen in the kiln, to diminish or terminate oxidation even though sufficient temperatures and residence times are maintained. Thus it has been found that considerable amounts of incompletely incinerated hazardous waste can escape from the rotary kiln each time a drum filled with hazardous waste is supplied to the rotary kiln. Obviously, it is undesirable for such unincinerated hazardous waste to be emitted into the atmosphere.
It is, accordingly, an object of the present invention to provide a new and improved method of incinerating hazardous organic liquid-like waste.
Another object of the invention is to provide a new and improved container for liquid-like, organic hazardous waste, wherein the container is constructed to enable the waste to be more completely incinerated in a rotary kiln.
A further object of the invention is to provide a new and improved method of supplying liquid-like organic hazardous waste to a rotary kiln used to incinerate the waste wherein there is a substantial reduction of transient gaseous emissions resulting from unincinerated hazardous waste.
Still another object of the invention is to provide a new and improved method of supplying liquidlike organic hazardous waste to a rotary kiln used to incinerate the waste so that the time required to volatilize or vaporize the waste is substantially increased, thereby to enable more complete incineration of the waste and reduce the amount of hazardous materials emitted by an incinerator system.
A further object of the invention is to provide a new and improved container for liquid-like organic hazardous waste to be used with a rotary incinerator kiln, wherein the container is constructed to substantially reduce transient gaseous emissions resulting from unincinerated or partially incinerated hazardous waste.